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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
//
//
//
// Contents: Full text implementation of the specialized text line representing
// state of line up to the point where line break may occur
//
// Spec: Text Formatting API.doc
//
//
using System;
using System.Security;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Media;
using System.Windows.Media.TextFormatting;
using MS.Internal.PresentationCore;
using SR = MS.Internal.PresentationCore.SR;
namespace MS.Internal.TextFormatting
{
/// <summary>
/// Full text implementation of the specialized text line representing state
/// of line up to the point where line break may occur. Unlike a more tangible
/// type like text line , breakpoint could not draw or performs hit-testing
/// operation. It could only reflect formatting result back to the client.
/// </summary>
internal sealed class FullTextBreakpoint : TextBreakpoint
{
private TextMetrics _metrics; // full text metrics
private IntPtr _ploline; // native object representing this break
private IntPtr _penaltyResource; // unsafe handle to the internal factors used to determines penalty of the break. By default, the lifetime of this resource is managed by _ploline.
private bool _isDisposed; // flag indicates whether this object is disposed
private bool _isLineTruncated; // flag indicates whether the line produced at this breakpoint is truncated.
/// <summary>
/// Construct a list of potential breakpoints starting from the specified firstCharIndex
/// </summary>
/// <param name="paragraphCache">cache of paragraph content of all possible breaks within</param>
/// <param name="firstCharIndex">index to first character where formatting starts</param>
/// <param name="maxLineWidth">max format ideal width of the line being built</param>
/// <param name="previousLineBreak">LineBreak property of the previous text line, or null if this is the first line in the paragraph</param>
/// <param name="penaltyRestriction">constraint on what breakpoint is returned based on its implied calculated penalty</param>
/// <param name="bestFitIndex">index of the best fit breakpoint in the returned collection</param>
/// <returns>a list of potential breakpoints starting from firstCharIndex</returns>
internal static IList<TextBreakpoint> CreateMultiple(
TextParagraphCache paragraphCache,
int firstCharIndex,
int maxLineWidth,
TextLineBreak previousLineBreak,
IntPtr penaltyRestriction,
out int bestFitIndex
)
{
Invariant.Assert(paragraphCache != null);
// grab full text state from paragraph cache
FullTextState fullText = paragraphCache.FullText;
Invariant.Assert(fullText != null);
FormatSettings settings = fullText.TextStore.Settings;
Invariant.Assert(settings != null);
// update formatting parameters at line start
settings.UpdateSettingsForCurrentLine(
maxLineWidth,
previousLineBreak,
(firstCharIndex == fullText.TextStore.CpFirst)
);
Invariant.Assert(settings.Formatter != null);
// acquiring LS context
TextFormatterContext context = settings.Formatter.AcquireContext(fullText, IntPtr.Zero);
IntPtr previousBreakRecord = IntPtr.Zero;
if (settings.PreviousLineBreak != null)
previousBreakRecord = settings.PreviousLineBreak.BreakRecord;
// need not consider marker as tab since marker does not affect line metrics and it wasnt drawn.
fullText.SetTabs(context);
LsBreaks lsbreaks = new LsBreaks();
LsErr lserr = context.CreateBreaks(
fullText.GetBreakpointInternalCp(firstCharIndex),
previousBreakRecord,
paragraphCache.Ploparabreak, // para breaking session
penaltyRestriction,
ref lsbreaks,
out bestFitIndex
);
// get the exception in context before it is released
Exception callbackException = context.CallbackException;
// release the context
context.Release();
if(lserr != LsErr.None)
{
if(callbackException != null)
{
// rethrow exception thrown in callbacks
throw callbackException;
}
else
{
// throw with LS error codes
TextFormatterContext.ThrowExceptionFromLsError(SR.Format(SR.CreateBreaksFailure, lserr), lserr);
}
}
// keep context alive at least till here
GC.KeepAlive(context);
TextBreakpoint[] breakpoints = new TextBreakpoint[lsbreaks.cBreaks];
for (int i = 0; i < lsbreaks.cBreaks; i++)
{
breakpoints[i] = new FullTextBreakpoint(
fullText,
firstCharIndex,
maxLineWidth,
ref lsbreaks,
i // the current break
);
}
return breakpoints;
}
/// <summary>
/// Construct breakpoint from full text info
/// </summary>
private FullTextBreakpoint(
FullTextState fullText,
int firstCharIndex,
int maxLineWidth,
ref LsBreaks lsbreaks,
int breakIndex
) : this()
{
// According to antons: PTS only uses the width of a feasible break to avoid
// clipping in subpage. At the moment, there is no good solution as of how
// PTS client would be able to compute this width efficiently using LS.
// The work around - although could be conceived would simply be too slow.
// The width should therefore be set to the paragraph width for the time being.
//
// Client of text formatter would simply pass the value of TextBreakpoint.Width
// back to PTS pfnFormatLineVariants call.
LsLineWidths lineWidths = new LsLineWidths();
lineWidths.upLimLine = maxLineWidth;
lineWidths.upStartMainText = fullText.TextStore.Settings.TextIndent;
lineWidths.upStartMarker = lineWidths.upStartMainText;
lineWidths.upStartTrailing = lineWidths.upLimLine;
lineWidths.upMinStartTrailing = lineWidths.upStartTrailing;
// construct the correspondent text metrics
unsafe
{
_metrics.Compute(
fullText,
firstCharIndex,
maxLineWidth,
null, // collapsingSymbol
ref lineWidths,
&lsbreaks.plslinfoArray[breakIndex]
);
_ploline = lsbreaks.pplolineArray[breakIndex];
// keep the line penalty handle
_penaltyResource = lsbreaks.plinepenaltyArray[breakIndex];
if (lsbreaks.plslinfoArray[breakIndex].fForcedBreak != 0)
_isLineTruncated = true;
}
}
/// <summary>
/// Empty private constructor
/// </summary>
private FullTextBreakpoint()
{
_metrics = new TextMetrics();
}
/// <summary>
/// Finalizing the break
/// </summary>
~FullTextBreakpoint()
{
Dispose(false);
}
/// <summary>
/// Disposing LS unmanaged memory for text line
/// </summary>
protected override void Dispose(bool disposing)
{
if(_ploline != IntPtr.Zero)
{
UnsafeNativeMethods.LoDisposeLine(_ploline, !disposing);
_ploline = IntPtr.Zero;
_penaltyResource = IntPtr.Zero;
_isDisposed = true;
GC.KeepAlive(this);
}
}
#region TextBreakpoint
/// <summary>
/// Client to acquire a state at the point where breakpoint is determined by line breaking process;
/// can be null when the line ends by the ending of the paragraph. Client may pass this
/// value back to TextFormatter as an input argument to TextFormatter.FormatParagraphBreakpoints when
/// formatting the next set of breakpoints within the same paragraph.
/// </summary>
public override TextLineBreak GetTextLineBreak()
{
if (_isDisposed)
{
throw new ObjectDisposedException(SR.TextBreakpointHasBeenDisposed);
}
return _metrics.GetTextLineBreak(_ploline);
}
/// <summary>
/// Client to get the handle of the internal factors that are used to determine penalty of this breakpoint.
/// </summary>
/// <remarks>
/// Calling this method means that the client will now manage the lifetime of this unmanaged resource themselves using unsafe penalty handler.
/// We would make a correspondent call to notify our unmanaged wrapper to release them from duty of managing this
/// resource.
/// </remarks>
internal override IntPtr GetTextPenaltyResource()
{
if (_isDisposed)
{
throw new ObjectDisposedException(SR.TextBreakpointHasBeenDisposed);
}
LsErr lserr = UnsafeNativeMethods.LoRelievePenaltyResource(_ploline);
if (lserr != LsErr.None)
{
TextFormatterContext.ThrowExceptionFromLsError(SR.Format(SR.RelievePenaltyResourceFailure, lserr), lserr);
}
return _penaltyResource;
}
/// <summary>
/// Client to get a Boolean flag indicating whether the line is truncated in the
/// middle of a word. This flag is set only when TextParagraphProperties.TextWrapping
/// is set to TextWrapping.Wrap and a single word is longer than the formatting
/// paragraph width. In such situation, TextFormatter truncates the line in the middle
/// of the word to honor the desired behavior specified by TextWrapping.Wrap setting.
/// </summary>
public override bool IsTruncated
{
get { return _isLineTruncated; }
}
#endregion
#region TextMetrics
/// <summary>
/// Client to get the number of text source positions of this line
/// </summary>
public override int Length
{
get { return _metrics.Length; }
}
/// <summary>
/// Client to get the number of characters following the last character
/// of the line that may trigger reformatting of the current line.
/// </summary>
public override int DependentLength
{
get { return _metrics.DependentLength; }
}
/// <summary>
/// Client to get the number of newline characters at line end
/// </summary>
public override int NewlineLength
{
get { return _metrics.NewlineLength; }
}
/// <summary>
/// Client to get distance from paragraph start to line start
/// </summary>
public override double Start
{
get { return _metrics.Start; }
}
/// <summary>
/// Client to get the total width of this line
/// </summary>
public override double Width
{
get { return _metrics.Width; }
}
/// <summary>
/// Client to get the total width of this line including width of whitespace characters at the end of the line.
/// </summary>
public override double WidthIncludingTrailingWhitespace
{
get { return _metrics.WidthIncludingTrailingWhitespace; }
}
/// <summary>
/// Client to get the height of the line
/// </summary>
public override double Height
{
get { return _metrics.Height; }
}
/// <summary>
/// Client to get the height of the text (or other content) in the line; this property may differ from the Height
/// property if the client specified the line height
/// </summary>
public override double TextHeight
{
get { return _metrics.TextHeight; }
}
/// <summary>
/// Client to get the distance from top to baseline of this text line
/// </summary>
public override double Baseline
{
get { return _metrics.Baseline; }
}
/// <summary>
/// Client to get the distance from the top of the text (or other content) to the baseline of this text line;
/// this property may differ from the Baseline property if the client specified the line height
/// </summary>
public override double TextBaseline
{
get { return _metrics.TextBaseline; }
}
/// <summary>
/// Client to get the distance from the before edge of line height
/// to the baseline of marker of the line if any.
/// </summary>
public override double MarkerBaseline
{
get { return _metrics.MarkerBaseline; }
}
/// <summary>
/// Client to get the overall height of the list items marker of the line if any.
/// </summary>
public override double MarkerHeight
{
get { return _metrics.MarkerHeight; }
}
#endregion
}
}
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